Okay, here is the explanation of how a send/return loop works, based on the provided information.
A send return, often referred to as an FX loop, is a common feature on guitar and bass amplifiers that provides a dedicated path for connecting effects pedals or other audio processors. It essentially creates an interruption point in the amplifier's internal signal chain, allowing external gear to be inserted after the preamp section and before the power amp section.
Here's the breakdown of the signal flow:
- Signal Exits the Amp (The SEND): The amplifier processes the instrument signal through its preamp section. This is where the initial amplification, gain, EQ (bass, middle, treble), and often the amplifier's core overdrive or distortion character are shaped. According to the reference, the FX loop sends the post amplified/equalized signal out of the amp (The SEND jack). This means the signal coming out of the SEND jack has already been shaped by the amp's preamp.
- Signal Enters Effect Pedal: The signal from the amp's SEND jack is connected to the input of an effect pedal (or a chain of pedals).
- Signal is Processed: The effect pedal modifies the signal (e.g., adds delay, reverb, chorus, modulation). That signal is then processed through the pedal.
- Signal Returns to the Amp (The RETURN): The processed signal from the output of the effect pedal is connected back to the amplifier's RETURN jack.
- Signal Continues Amp Processing: The signal entering the RETURN jack is fed back into the amplifier. ...and fed back into the amp before the Power Amp section of the amplifier (The RETURN jack). This means the effect is applied to the signal before it reaches the power amplifier, which boosts the signal to a level capable of driving the speaker.
- Signal Goes to Speaker: The signal, now processed by the preamp and the external effect, goes through the power amp and then to the speaker, where it is finally heard.
Why Use a Send Return?
Placing certain effects in the send/return loop, rather than directly between the instrument and the amp's input, offers significant advantages, particularly for effects that work best applied after the amp's gain or overdrive.
- Optimal Placement for Time-Based & Modulation Effects: Effects like delay, reverb, chorus, flanger, and phaser often sound much clearer and more natural when placed after the preamp's distortion. Placing them before a distorted preamp can make them sound muddy or cause the repeats/modulation to distort in an undesirable way.
- Preserving Preamp Tone: Using the loop ensures that the core tone generated by your amp's preamp (including its specific overdrive characteristics) remains intact before the external effect is applied.
Signal Flow Comparison
Here's a simple table illustrating the difference:
| Connection Type | Signal Path | Typical Effects Placement |
|---|---|---|
| Direct to Input | Instrument → Effect(s) → Amp Input → Preamp → Power Amp → Speaker | Overdrive, Distortion, Wah, Compression, EQ |
| Via Send/Return Loop | Instrument → Amp Input → Preamp → SEND → Effect(s) → RETURN → Power Amp → Speaker | Delay, Reverb, Chorus, Flanger, Phaser, Volume Pedal (for overall level) |
Practical Example
Imagine you're using an amplifier with built-in overdrive and you want to add a delay effect.
- Putting Delay Before Amp Input: Instrument -> Delay Pedal -> Amp Input. The delay repeats would be fed into the overdriven preamp, potentially causing them to distort and sound unclear, especially at higher delay feedback settings.
- Putting Delay in FX Loop: Instrument -> Amp Input. Amp SEND -> Delay Pedal Input. Delay Pedal Output -> Amp RETURN. The preamp creates the overdriven tone. This overdriven signal then goes to the delay pedal. The delay pedal adds clean repetitions of the overdriven signal. These clean repeats are then sent back to the power amp, resulting in clear delay trails layered over your distorted amp tone.
In summary, the send/return loop provides a vital access point in an amplifier's signal path, allowing you to insert effects precisely where they often sound best – after the initial tone shaping of the preamp but before the final boost to the speaker.
